BEIJING (AP) _ An explosion killed at least 46 coal miners in a Chinese mine that had illegally reopened after being closed for safety reasons, state media and a local official said Monday.

Thirteen miners were rescued after the explosion Sunday at the mine in Xuzhou, a city in the eastern province of Jiangsu. But as many as 47 miners were missing, according to figures reported earlier.

Those still trapped had no hope of survival, the official Xinhua News Agency said.

Premier Zhu Rongji ordered an ``all-out effort'' to save the trapped miners, and the government again demanded the closure of unlicensed coal mines, saying they were as dangerous as ``time bombs,'' Xinhua said.

The blast in the Xuzhou mine might have occurred in the coal bed or gas that collected in a tunnel, according to Xinhua, which added that production at more than 100 other small mines in Xuzhou was halted for safety reviews.

The mine that exploded was closed June 15 because it lacked ``all necessary ... safety facilities'' but it reopened this month, said a local official who identified himself only as Mr. Jiang.

Police have detained the mine owner, Jiang said by telephone.

The government sent its chief official for industrial safety, Zhang Baoming, to Xuzhou after the explosion.

Last week, Zhang had called for urgent measures to improve safety after explosives stored illegally in a northern Chinese blew up, killing at least 69 people.

China's coal mines are the world's deadliest, suffering thousands of deaths a year. This month, 21 miners were reported killed when a mine flooded in the northeastern province of Jilin.